Assessing the utility of confirmatory studies following identification of large-scale genomic imbalances by microarray.

PURPOSE: The identification of clinically relevant genomic dosage anomalies assists in accurate diagnosis, prognosis, and medical management of affected individuals. Technological advancements within the field, such as the advent of microarray, have markedly increased the resolution of detection; however, clinical laboratories have maintained conventional techniques for confirmation of genomic imbalances identified by microarray to ensure diagnostic accuracy. In recent years the utility of this confirmatory testing of large-scale aberrations has been questioned but has not been scientifically addressed. METHODS: We retrospectively reviewed 519 laboratory cases with genomic imbalances meeting reportable criteria by microarray and subsequently confirmed with a second technology, primarily fluorescence in situ hybridization. RESULTS: All genomic imbalances meeting reportable criteria detected by microarray were confirmed with a second technology. Microarray analysis generated no false-positive results. CONCLUSION: Confirmatory testing of large-scale genomic imbalances (deletion of ≥150 kb, duplication of ≥500 kb) solely for the purpose of microarray verification may be unwarranted. In some cases, however, adjunct testing is necessary to overcome limitations inherent to microarray. A recommended clinical strategy for adjunct testing following identified genomic imbalances using microarray is detailed.

Molecular characteristics of mantle cell lymphoma presenting with clonal plasma cell component.

The normal counterparts of mantle cell lymphoma (MCL) are naive, quiescent B cells that have not been processed through the germinal center (GC). For this reason, although lymphomas arising from GC or post-GC B cells often exhibit plasmacytic differentiation, MCL rarely presents with plasmacytic features. Seven cases of MCL with a monotypic plasma cell (PC) population were collected from 6 centers and were studied by immunohistochemistry, fluorescence immunophenotyping and interphase cytogenetics as a tool for the investigation of neoplasms analysis, capillary gel electrophoresis, and restriction fragment length polymorphism of immunoglobulin heavy chain analysis of microdissections of each of the MCL and PC populations to assess their clonal relationship. The clinical presentation was rather unusual compared with typical MCL, with 2 cases arising from the extranodal soft tissues of the head. All MCL cases were morphologically and immunohistochemically typical, bearing the t(11;14)(q13;q32). In all cases, the PC population was clonal. In 5 of the 7 cases, the MCL and PC clones showed identical restriction fragments, indicating a common clonal origin of the neoplastic population. The 2 cases with clonal diversity denoted the coexistence of 2 different tumors in a composite lymphoma/PC neoplasm. Our findings suggest that MCL can present with a PC component that is often clonally related to the lymphoma, representing a rare but unique biological variant of this tumor.

Chronic lymphocytic leukemia with paraimmunoblastic transformation - with comparative genomic hybridization and review of the literature.

Richter's transformation (RT) is the development of a high-grade lymphoma in patients with B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). We report an extremely rare case with paraimmunoblastic transformation. A 78-year-old Taiwanese male had Rai stage 1 and Binet stage B CLL/SLL involving skin, peripheral blood (PB), and bone marrow (BM) with paraimmunoblastic transformation in the lymph node. Molecular/genomic studies showed the same clonal origin of tumor tissues at various locations with trisomy 12 and a deletion of chromosome 13q14. Interestingly, there seemed to be no additional chromosomal aberrations in the transformed nodal tissue, suggesting that the micro-environment rather than an additional genetic lesion contributed to the transformation. The patient received chemotherapy and was alive with disease after 33.5 months.

Primary bone diffuse large B-cell lymphoma: clinicopathologic study of 21 cases and review of literature.

Primary bone diffuse large B-cell lymphomas (PB-DLBCL) are uncommon extranodal lymphomas. Herein, we report the clinical, pathologic, immunohistochemical, and molecular features of 21 cases of PB-DLBCL. The mean age of the patients was 54 years (range: 13 to 85 y). The male and female ratio was 1.6:1. The tumors consisted of diffuse sheets of large atypical cells or a polymorphous mixture of small-to-large cells with large multilobated nuclei, fine chromatin, and inconspicuous to prominent nucleoli. Twelve (57%) cases were non-germinal center B (GCB) and 9 (43%) were GCB subtype based on immunohistochemical classification. B-cell lymphomas (BCL)-2 was positive in 17/21 (81%), TP53 in 11/21 (52%) positive and the mean MIB-1 index was 57%. Polymerase chain reaction showed 10 cases with immunoglobulin heavy-chain (IGH) and 4 cases with IGH/BCL-2 gene rearrangement. The fluorescence in-situ hybridization analyses showed 14% of cases with BCL-6, 19% of cases with BCL-2, and 9% of cases with C-MYC gene rearrangement. Age <60 years and complete response to initial treatment were significant predictors of survival outcome (P< or =0.05). Even though no association was observed between the subtype of PB-DLBCL (GCB vs. non-GCB), BCL2, TP53, MIB1 index and overall survival (P>0.05), due to small sample size, and variability in treatment received, this analysis may be interpreted with caution.

9q34 rearrangements in BCR/ABL fusion-negative acute lymphoblastic leukemia.

The t(9;22)(q11.2;q34) translocation is found in a subset of acute lymphoblastic leukemia (ALL). The presence of this translocation involving the fusion of BCR/ABL genes represents a poor prognostic group. Because of the importance in detecting t(9;22) in ALL patients and because occasionally a cytogenetically cryptic BCR/ABL fusion is detected with fluorescence in situ hybridization (FISH), our laboratory routinely performs BCR/ABL FISH tests on all newly diagnosed ALL patients. In the past year, 25 consecutive, newly diagnosed, untreated ALL cases were analyzed. We report the cytogenetics and FISH findings of three cases containing a rearranged 9q34 region with an intact BCR (22q11.2) region and an absence of the BCR/ABL fusion. A split ABL signal representing a translocation of the 9q34 region with chromosome segments other than 22q11.2 (BCR) was observed in 3 cases. Two of these patients were 3 years old; one was 21 at the time of diagnosis. A split ABL FISH signal without the involvement of BCR does not represent a t(9;22) translocation, and prognostic implications of this apparent subgroup of ALL cases have not been determined. Cytogenetic, pathologic, and clinical aspects of these three cases are presented.

Interphase fluorescence in situ hybridization studies for the detection of 9q34 deletions in chronic myelogenous leukemia: a practical approach to clinical diagnosis.

Chronic myelogenous leukemia (CML) is characterized by the Philadelphia chromosome (Ph) in more than 90% of cases. Recent studies using fluorescence in situ hybridization (FISH) have shown that in a subset of patients with CML, deletions of 9q34 involving the argininosuccinate synthetase region occur at the time of the Philadelphia translocation and are associated with a poor prognosis. We performed interphase FISH studies in 152 cases of CML using a dual-color, dual-fusion probe system with a third probe directed at 9q34. Cytogenetic studies showed a simple (typical) Ph in 124/152 (82%), a cryptic Ph in 11/152 (7%), and a variant Ph chromosome with a complex translocation in 17/152 (11%) of cases. Interphase FISH studies showed single BCR/ABL fusion patterns in 48/152 (32%) of cases. Deletions of 9q34 were observed in 14% of all the cases and were present in 46% of cases with single BCR/ABL fusion pattern. All the 9q34 deletions occurred in cases with single BCR/ABL fusion signal. However, a single-fusion pattern is not specific for 9q34 deletions, and cases should be routinely screened for the presence of this prognostically significant abnormality by using a third probe directed specifically at 9q34.